Inside Macintosh: QuickTime Components
Video digitizer components provide several functions that allow applications to specify the destination for the digitized video stream produced by the digitizer component. You have two options for specifying the destination for the video data stream in your application.
The first option requires that the video be digitized as RGB pixels and placed into a destination pixel map. This option allows the video to be placed either onscreen or offscreen, depending upon the placement of the pixel map. Your application can use the VDSetPlayThruDestination function (described on VDSetPlayThruDestination ) to set the characteristics for this option. Your application can use the VDPreflightDestination function (described on VDPreflightDestination ) to determine the capabilities of the digitizer. All video digitizer components must support this option.
The second option uses a global boundary rectangle to define the destination for the video. This option always results in onscreen images and is useful with digitizers that support hardware direct memory access (DMA) across multiple screens. The digitizer component is responsible for any required color depth conversions, image clipping and resizing, and so on. Your application can use the VDSetPlayThruGlobalRect function (described on VDSetPlayThruGlobalRect ) to set the characteristics for this option. Your application can use the VDPreflightGlobalRect function (described on VDPreflightGlobalRect ) to determine the capabilities of the digitizer. Not all video digitizer components support this option.